Arabic Abstract

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English Abstract

A flow injection spectrophotometric method was successrully applied to the determination of tetracycline HC1, oxytetracycline, chlorotetracycline, and demeclocycline. Both, the univarient and the simplex method of optimization were adopted for the selection of the proper experimental conditions, that is, the chemical and flow injection parameters. In the method 157 ul sample was injected, for all compounds, into the carrier stream of iron(III) solution of concentration 554, 626, 701, and 447 ppm flowing at rates of 3.72, 3.72, 4.37, and 3.72 m1/min, thus passing through reaction coils of a lengths of 55, 45, 85, and 45 cm respectively. 0.111M Sulphuric acid was used as an overall reaction medium. These experimental conditions were attained by the modified simplex method and were considered for the determination of the above compounds. Very high sampling frequency of the order of at lest 170 samples per hour was attained for all compounds. High precision with a relative standard deviation of less than 0.9 was obtained. The accuracy was found to be high when the results were compared to those obtained by the conventional spectrophotometric method. The present method was applied to the determination of tetracycline or its derivatives in propietry drugs in both capsules and injection formulation, and interferences from exciepients was found to be insignificant.